Polymer precursor dispersion containing a micropulp and method of making the dispersion

ABSTRACT

This invention relates to a polymer precursor dispersion for use in making a polymer that is a solid at room temperature and further relates to a method of making same where the dispersion comprises a polymer precursor comprising an addition monomer, a condensation monomer, a prepolymer, or a polymer modifier and 0.01 to 50 weight percent of a micropulp having a volume average length of from 0.01 to 100 micrometers.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention is directed to a process for incorporating amicropulp in a polymer precursor, the resulting dispersion, polymer madefrom that dispersion, and articles made from that polymer.

[0003] 2. Description of Related Art

[0004] Pulps, because of their fibrous nature, can be difficult touniformly disperse in other materials. Many polymers can be enhanced bythe addition of a pulp, and even very small additions of pulp can have apositive effect.

[0005] U.S. patent application Ser. No. 10/295,455 filed Nov. 15, 2002relates to a process for producing micropulp in a liquid component anddiscloses that liquid component can be an aqueous liquid, one or moreliquid polymers, one or more solvents, or a combination thereof.

[0006] U.S. patent application Ser. No. 10/295,341 filed Nov. 15, 2002relates to coating compositions made from a dispersion of micropulp in aliquid component selected from the group consisting of an aqueousliquid, one or more liquid polymers, one or more solvents, or acombination thereof.

[0007] U.S. patent application Ser. No. 10/401,347 filed on Mar. 28,2003 relates to a liquid nail polish compositions containing micropulpwherein the micropulp is made in a nail polish resin system comprising aresin and a solvent.

[0008] U.S. patent application 60/462,236 filed on Apr. 11, 2003 relatesto coating compositions and molded products containing acetoacetylatedpolyvinyl polymers and discloses a method of producing a molded articlecomprising mixing micropulp with a composition comprisingacetoacetylated polyvinyl polymers, melting the polymers and then makinga molded shape from the mixture of micropulp and polymer.

[0009] All of these references concern the formation and incorporationof a micropulp in a liquid polymer or a polymer solutioned in a solvent.However many polymers are not available in a useable liquid form, eitherdue to high viscosity or because they are solid at room temperature, andsome of these polymers are either not suited to be liquefied via thermalor other means.

BRIEF SUMMARY OF THE INVENTION

[0010] This invention is directed to a polymer precursor dispersion foruse in making a polymer that is a solid at room temperature, comprisinga polymer precursor comprising an addition monomer, a condensationmonomer, a prepolymer, or a polymer modifier; and a micropulp having avolume average length of from 0.01 to 100 micrometers, the micropulpcomprising 0.01 to 50 weight percent of the dispersion.

[0011] This invention is further directed to a method of incorporating amicropulp in a polymer precursor for making a polymer that is a solid atroom temperature, comprising contacting organic fiber, a polymerprecursor and a solid component, agitating the organic fiber, thepolymer precursor, and the solid component to transform the organicfiber into a micropulp having a volume average length of from 0.01 to100 micrometers dispersed in the polymer precursor, and optionallyremoving the solid component.

DETAILED DESCRIPTION OF THE INVENTION

[0012] This invention relates to a polymer precursor dispersioncontaining a micropulp and a method of incorporating a micropulp in apolymer precursor for making a polymer. This polymer precursordispersion can then be reacted, polymerized, or otherwise combined witha polymer to create a polymer having dispersed therein a micropulp.

Polymer Precursor Dispersion

[0013] The polymer precursor dispersion of the present invention is foruse in making a polymer that is a solid at room temperature. Thedispersion comprises a polymer precursor comprising an addition monomer,a condensation monomer, a prepolymer, or a polymer modifier. Thedispersion further comprises a micropulp having a volume average lengthof from 0.01 to 100 micrometers, the micropulp comprising 0.01 to 50weight percent of the dispersion.

[0014] Micropulp

[0015] As used herein, micropulp is a processed organic fiber having avolume average length ranging from 0.01 to 100 micrometers, preferably0.1 to 50 micrometers. Such micropulps generally have an average surfacearea ranging from 25 to 500 square meters per gram. The micropulp of thepresent invention is a fibrous organic material that includes anintermeshed combination of two or more webbed, dendritic, branched,mushroomed or fibril structures.

[0016] Micropulp is made by contacting an organic fiber with a mediumcomprised of a liquid component and a solid component and then agitatingthe combination to size reduce and modify the organic fiber. The organicfiber used as a starting material can include pulp, short fiber, fibridsor mixtures of these forms. Through this treatment the micropulp isuniformly dispersed in the liquid component.

[0017] Pulps can be made by refining short fibers between rotating discsto cut and shear the fibers into smaller pieces. Pulp particles differfrom short fibers by having a multitude of fibrils or tentaclesextending from the body of each pulp particle. These fibrils ortentacles provide minute hair-like anchors for reinforcing compositematerials and cause the pulp to have a very high surface area. Aparticularly useful starting material is aramid pulp, which is wellknown in the art and can be made by refining aramid fibers to fibrillatethe short pieces of aramid fiber material. Such pulps have been reportedto have a surface area in the range of 4.2 to 15 meters²/gram and aKajaani weight average length in the range of 0.6 to 1.1 millimeters(mm). Such pulps have high volume average length, compared to themicropulp. For example, Style 1F543 aramid pulp available from E. I. duPont de Nemours and Company has a Kajaani weight average length in therange of 0.6 to 0.8 mm, and when laser detraction is used to measurethis pulp the volume average length is 500 to 600 micrometers (0.5 to0.6 mm). An alternate method of making aramid pulp directly from apolymerizing solution is disclosed in U.S. Pat. No. 5,028,372.

[0018] Short fiber (sometimes called floc) is made by cutting continuousfilament into short lengths without significantly fibrillating thefiber. Short fiber length typically ranges from about 0.25 mm to 12 mm.Short fibers suitable for use in the present invention are thereinforcing fibers disclosed in U.S. Pat. No. 5,474,842.

[0019] Fibrids are non-granular film-like particles having an averagemaximum length or dimension in the range of 0.2 to 1 mm with alength-to-width aspect ratio in the range of 5:1 to 10:1. The thicknessdimension is on the order of a fraction of a micron. Aramid fibrids arewell known in the art and can be made in accordance with the processesdisclosed in U.S. Pat. Nos. 5,209,877, 5,026,456, 3,018,091 and2,999,788. The processes typically include adding a solution of organicpolymer in solvent to another liquid, that is a non-solvent for thepolymer but is miscible with the solvent, and applying vigorousagitation to cause coagulation of fibrids. The coagulated fibrids arewet milled, separated, and dried to yield clumps of fibrids having ahigh surface area; the clumps are then opened to yield a particulatefibrid product.

[0020] Micropulp used in the present invention can be made from anorganic fiber comprised of aliphatic polyamides, polyesters,polyacrylonitriles, polyvinyl alcohols, polyolefins, polyvinylchlorides, polyvinylidene chlorides, polyurethanes, polyfluorocarbons,phenolics, polybenzimidazoles, polyphenylenetriazoles, polyphenylenesulfides, polyoxadiazoles, polyimides, aromatic polyamides, or a mixturethereof. Especially useful polymers are made from aromatic polyamides,polybenzoxadiazole, polybenzimidazole, or a mixture thereof. Otherorganic fibers suitable for use in the present invention include naturalfibers, such as cellulose, cotton, silk, and/or wool fibers.

[0021] Some commercially available fibers useful as a starting materialfor micropulp include ZYLON® PBO-AS(poly(p-phenylene-2,6-benzobisoxazole)) fiber, ZYLON® PBO-HM(poly(p-phenylene-2,6-benzobisoxazole)) fiber, DYNEEMA® SK60 and SK71ultra high strength polyethylene fiber, all supplied by Toyobo, Japan;Celanese VECTRAN® HS pulp, EFT 1063-178, supplied by Engineering FibersTechnology, Shelton, Conn.; CFF Fibrillated Acrylic Fiber supplied bySterling Fibers, Inc., Pace, Fla.; and Tiara Aramid KY-400S Pulpsupplied by Daicel Chemical Industries, Ltd., 1 Teppo-Cho, Sakai CityJapan.

[0022] The preferred organic fibers comprise fibers made from thearomatic polyamide polymers poly(p-phenylene terephthalamide) and/orpoly(m-phenylene isophthalamide). Such fibers are also known as aramidfibers. As used herein, “aramid” is meant a polyamide wherein at least85% of the amide (—CONH—) linkages are attached directly to two aromaticrings. Additives can be used with the aramid. In fact, it has been foundthat up to as much as 10 percent, by weight, of other polymeric materialcan be blended with the aramid or that copolymers can be used having asmuch as 10 percent of other diamine substituted for the diamine of thearamid or as much as 10 percent of other diacid chloride substituted forthe diacid chloride of the aramid. Such organic fibers are disclosed inU.S. Pat. Nos. 3,869,430; 3,869,429; 3,767,756; and 2,999,788. Preferredaromatic polyamide organic fibers are known under the trademark KEVLAR®fibers, KEVLAR® aramid pulp, style 1F543; 1.5 mm KEVLAR® aramid flocstyle 6F561; and NOMEX® aramid fibrids style F25W. All of these areavailable from E. I. du Pont de Nemours and Company, Wilmington, Del.

[0023] Polymer Precursor

[0024] The polymer precursor of this invention can be an additionmonomer, a condensation monomer, or a prepolymer or a polymer modifier.

[0025] Addition monomers are well known in the art and a non-limitingexample is methyl methacrylate, which can polymerize with itself to makepoly(methyl methacrylate), or with other monomers such as ethyl acrylateto make an acrylate compolymer. Other addition monomers useful in thisinvention include vinyl monomers such as styrene, acrylonitrile, andvinyl chloride.

[0026] Condensation monomers are also well known in the art and for thepurposes of this invention can be one or more of the reactants used in acondensation reaction to form a monomer or polymer, or one of the actualmonomers formed by the reactants. One useful but non-limiting example ofa condensation monomer is ethylene glycol, which can be reacted withdimethyl terephalate and used to form the polymer polyethyleneterephthalate. Other condensation monomers useful in this inventioninclude diethylene glycol, 1,3 propane diol, 1,4 butane diol, orcyclohexane dimethanol.

[0027] A prepolymer is a partially polymerized polymer that has lowmolecular weight and can be further polymerized to a higher molecularweight. By partially polymerized it is meant the reacting monomers arenot present in the proper stoichiometric ratio for fully polymer chaindevelopment, which prevents the generation of high molecular weight.Such proper stoichiometric ratio of monomers is normally 1:1 for manypolymers. Such prepolymers have low molecular weight, meaning they areonly able to form very short chains having only a few repeat units,normally less than about 20 repeat units, and typically less than about10 repeat units. A non-limiting example of a prepolymer is a polyamideacid. After a polymer precursor dispersion of micropulp and polyamideacid is made, a polymer is then made from the dispersion by firstadjusting the stoichiometric ratio of the prepolymer by addingadditional monomer. The polymer is then made by imidizing the prepolymerby heat to make a polyimide polymer. Other useful prepolymers caninclude any low molecular weight oligomers that can subsequently bepolymerized, such as a polyester oligomer. For the purposes of thisinvention, a prepolymer can also be an emulsified polymer dispersionthat is further reacted to form a useful polymer. For example, some acidcopolymers can be reacted with metal salts to form intractable polymercompositions. Micropulp can be incorporated into these polymers by firstproducing the micropulp in an emulsion of the acid copolymer. Theresulting polymer precursor dispersion can then be used to form thepolymer. A non-limiting example of a suitable acid copolymer is anethylene copolymer containing the polar comonomer methacrylic acid.

[0028] The polymer precursor can also be a polymer modifier. For thepurposes of this invention, a polymer modifier is a material that iscompatible with and substantially remains in the final polymer. Thepolymer modifier is not meant to be a solvent for the final polymer or apolymer itself, but modifies the final polymer in some way. For example,a polymer modifier can be an additive such as a plasticizer for thepolymer or a curing agent for the polymer. Other types of polymermodifier can function, for example, as a property enhancer, a processingaid, or a surface lubricating agent. A non-limiting example of a polymermodifier is a liquid fatty acid such as oleic acid, which can becombined with an ethylene-copolymer-based acid copolymer or ionomerwhile it is being mixed and neutralized. This polymer modifier oleateenhances the resilience of the polymer.

[0029] The preferred polymer precursors used in this invention have aviscosity at room temperature of less than 10,000 centipoise. Above10,000 centipoise, the liquid viscosity can be too high to adequatelyincorporate and process the organic fiber into a micropulp.

[0030] Solid Components

[0031] The shape of the solid component that is contacted with thepolymer precursor and the organic fiber is not critical and can includespheroids, diagonals, irregularly shaped particles or combinationsthereof. Spheroids are preferred. The maximum average size of the solidcomponent can range from 10 micrometers to 127,000 micrometers, and itdepends upon the type of agitating device used to produce the micropulp.For example, when attritors are used, the size generally varies fromabout 0.6 mm diameter to about 25.4 mm. When media mills are used, thediameter generally varies from about 0.1 to 2.0 mm, preferably from 0.2to 2.0 mm. When ball mills are used, the diameter generally varies fromabout 3.2 mm (⅛″) to 76.2 mm (3.0 inches), preferably from 3.2 mm (⅛″)to 9.5 mm ({fraction (3/8)} inches). The solid component is generallychemically compatible with the liquid component and typical solidcomponents are made from glass, alumina, zirconium oxide, zirconiumsilicate, cerium-stabilized zirconium oxide, fused zirconia silica,steel, stainless steel, sand, tungsten carbide, silicon nitride, siliconcarbide, agate, mullite, flint, vitrified silica, borane nitrate,ceramics, chrome steel, carbon steel, cast stainless steel, plasticresin, or a combination thereof. Some of the plastic resins suitable forthe solid component include polystyrene, polycarbonate, and polyamide.Some of the glass suitable for the solid component includes lead-freesoda lime, borosilicate and black glass. Zirconium silicate can be fusedor sintered.

[0032] The most useful solid component are balls made of carbon steel,stainless steel, tungsten carbide or ceramic. If desired, a mixture ofballs having the same size but different composition or having varyingsizes can also be used. Ball diameter can range from about 0.1millimeters to 76.2 millimeters and preferably from about 0.4millimeters to 9.5 millimeters, more preferably from about 0.7millimeters to 3.18 millimeters. Solid components are readily availablefrom various sources, some of which include Glenn Mills, Inc., Clifton,N.J.; Fox Industries, Inc., Fairfield, N.J.; and Union Process, Akron,Ohio.

[0033] Polymer and Articles

[0034] Once the micropulp is incorporated into a polymer precursor, thepolymer precursor dispersion can be reacted, polymerized or otherwiseprocessed or converted into a polymer containing micropulp usingconventional methods. The polymer having a micropulp dispersed therein,made from the polymer precursor dispersion of this invention, can be anytype of thermoplastic, thermoset, or other type of polymer as long as itis a solid at room temperature. The polymer can be further processed inany conventional manner, such as spun, extruded, shaped or molded intovarious articles (including fibers and films) or parts. Since theprocess of incorporating the micropulp into the polymer almost assuresthe micropulp will be well dispersed, the shaped articles or parts willhave uniform mechanical properties. The extremely small size of themicropulp substantially eliminates the pluggage problems encounteredwhen shaping larger prior art pulps

Methods of Incorporating Micropulp

[0035] The method of incorporating a micropulp in a polymer precursorfor making a polymer that is a solid at room temperature, comprises acontacting step, an agitating step, and optionally a removing step. Thecontacting step comprises contacting organic fiber, a polymer precursorand a solid component. The agitating step comprises agitating theorganic fiber, the polymer precursor, and the solid component totransform the organic fiber into a micropulp having a volume averagelength of from 0.01 to 100 micrometers dispersed in the polymerprecursor. The optional removing step comprises optionally removing thesolid component.

[0036] Contacting Step

[0037] In this invention, micropulp is made in a polymer precursor thatis the liquid component in which the organic fiber is processed. Suchpolymer precursors, if liquid at normal temperatures, can be used neatwithout solvent. However, if the polymer precursor is solid, or tooviscous, the polymer precursor can be solutioned in a solvent and usedin that fashion. If the polymer precursor is used without solvent, it ispreferred the micropulp be present in an amount of 0.01 to 10 weightpercent, based on the total weight of the polymer precursor andmicropulp. If a solvent is added to the polymer precursor, the preferredamount of organic fiber present is 0.01 to 10 weight percent based onthe total amount of polymer precursor, fiber, and solvent present.However, a concentrated polymer precursor can be made by removing all ora portion of the solvent from the dispersion after the micropulp isformed. In this manner a polymer precursor having concentrations of 50weight percent micropulp or higher can be formed.

[0038] In the process for forming the polymer precursor dispersion ofthis invention, the organic fiber is processed, in the presence of apolymer precursor, into micropulp having a volume average length rangingfrom 0.01 micrometers to 100 micrometers, and an average surface area offrom 25 to 500 square meters per gram. This is accomplished bycontacting and agitating the organic fibers with a liquid polymerprecursor and a solid component. Agitating the organic fibers in thepresence of solid components size-reduce and modify the organic fibers.The organic fibers repeatedly come in contact with and are masticated bythe solid components maintained in an agitated state by, for example,one or more stirring arms of an attritor. Unlike the conventionalgrinding or chopping processes that tend to largely reduce only fiberlength, albeit with some increase in surface area and fibrillation, thesize reduction in the process of this invention results from bothlongitudinal separation of the organic fibers into substantially smallerdiameter fibers along with a length reduction. Average fiber lengthreductions of one, two or even greater orders of magnitude can beattained. The agitating step is continued for sufficient duration totransform the organic fibers into the micropulp. Moreover, it may bedesirable to incrementally transform the organic fiber into themicropulp in several passes by repeatedly passing the medium containingthe organic fibers through the agitation device.

[0039] Agitating Step

[0040] When the polymer precursor dispersion containing micropulp ismade by agitating a solid component and a liquid polymer precursor orpolymer precursor solution, the surface of the micropulp is fully wettedand uniformly distributed in the dispersion, with minimal agglomerationsor clumps.

[0041] The processing of organic fibers into micropulp can beaccomplished in any one or more types of agitating devices, including anattritor or a mill, and the devices can be batch or continuouslyoperated. Batch attritors are known in the art and those such asattritor models 01, 1-S, 10-S, 15-S, 30-S, 100-S and 200-S supplied byUnion Process, Inc., of Akron, Ohio are well suited for the process ofthe present invention. Another supplier of such devices is Glen MillsInc. of Clifton, N.J. Media mills are supplied by Premier Mills, ReadingPa., and some of their suitable mills include the Supermill HM and EHPmodels.

[0042] The preferred agitation device is an attritor, and preferably thesolid component is poured into the agitation chamber of the attritor andthen agitated by the stirring arms, after which the premix of organicfibers and liquid component is then poured into the chamber. Toaccelerate the rate of transformation, the solid component is circulatedduring the agitating step through an external passage that is typicallyconnected near the bottom and the top of the chamber for a verticalmedia mill. The rate at which the solid component is agitated dependsupon the physical and chemical make-up of the organic fibers beingtransformed, the size and type of the solid component, the duration ofthe transformation, as well as the size of the micropulp desired. Theagitation of the solid component in an attritor is generally controlledby the tip speed of the stirring arms and the number of stirring armsprovided. A typical attritor has four to twelve arms and the tip speedof the stirring arms generally range from about 150 fpm to about 1200fpm (about 45 meters per minute to about 366 meters per minute). Thepreferred attritor has six arms and is operated at a tip speed in therange of about 200 fpm to about 1000 fpm (about 61 meters per minute toabout 305 meters per minute) and more preferably from about 300 fpm toabout 500 fpm (about 91 meters per minute to about 152 meters perminute). If a media mill is used, the tip speeds of the stirring armsgenerally range from about 1500 fpm to about 3500 fpm (about 457 metersper minute to about 1067 meters per minute) and preferably from about2000 fpm to about 3000 fpm (about 610 meters per minute to about 914meters per minute). Any excessive heat generated in the agitationprocess is normally removed by use of a cooling jacket on the agitationchamber.

[0043] The amount of solid component used in the agitating chamber iscalled the load, and is measured by the bulk volume and not the actualvolume of the agitating chamber. Thus, 100% load means about 60% of thechamber volume since substantial air pockets exist within the solidcomponent. The load for the media mill or an attritor ranges from 40% to90%, preferably from 75% to 90% based on the full load. The load for theball mill ranges from 30% to 60% based on the full load. In practice,the percent load is determined by first totally filling the chamber withthe solid component to determine the weight of a full load. The desiredload is then measured by weight as a percent of the full load.

[0044] Optional Removing Step

[0045] After the organic fiber is transformed into a micropulp, normallythe solid component is removed to form a dispersion of the micropulp inthe polymer precursor. Typically the solid component remains in theagitating chamber. However, if needed, some of the conventionalseparation processes include a mesh screen having openings that aresmall enough for the polymer precursor dispersion containing themicropulp to pass through while the solid component is retained on themesh screen. Thereafter, the dispersion can be used directly. Typically,the dispersion of the preferred micropulp, when visually observed on a254 microns (10 mils) draw-down on a glass, contains negligible grit orseed.

Test Methods

[0046] Volume average length measurements were made using laserdiffraction using a Beckman LS Particle Size Analyzer. Single pointnitrogen BET surface area measurements were made using a Strohlein AreaMeter. As used herein, the volume average length is calculated by thefollowing equation: $\frac{\begin{matrix}{\sum{\left( {{number}\quad {of}\quad {fibers}\quad {of}\quad {given}\quad {length}} \right) \times}} \\\left( {{length}\quad {of}\quad {each}\quad {fiber}} \right)^{4}\end{matrix}}{\begin{matrix}{\sum{\left( {{number}\quad {of}\quad {fibers}\quad {of}\quad {given}\quad {length}} \right) \times}} \\\left( {{length}\quad {of}\quad {each}\quad {fiber}} \right)^{3}\end{matrix}}$

EXAMPLES

[0047] This invention will now be illustrated by the following specificexamples. All parts and percentages are by weight unless otherwiseindicated. Examples and samples prepared according to the process orprocesses of the current invention are indicated by numerical values.Control or Comparative Examples and samples are indicated by letters.

Example 1

[0048] This example illustrates a method for making a polymer precursordispersion of micropulp in a condensation monomer, and then polymerizingthe condensation monomer to make a polymer. For this example, thecondensation monomer is ethylene glycol and the final polymer is apolyester.

[0049] The polymer precursor dispersion was prepared by adding 300 gramsof poly(paraphenylene terephthalamide) pulp (KEVLAR® pulp Merge 1F543available from E. I. du Pont de Nemours and Company) to 12,908 grams ofethylene glycol in a tank to form a dispersion of pulp in ethyleneglycol having a pulp content of 2.27 weight percent. The pulp wasdispersed using a high speed disperser with a cowles blade running at aspeed high enough to create a vortex in the dispersion. The dispersionwas then recirculated through a 1.5 liter Premier SML Supermill. Themill was run with a circumferential disk speed of 2400 feet per minute(732 meters per minute) and after 8 hours of recirculation a sample ofthe dispersion of micropulp in ethylene glycol was collected. ThisSample 1 had a micropulp content of 2.27 weight percent. The remainingdispersion of micropulp in ethylene glycol was diluted with additionalethylene glycol until the micropulp content was 1.85 weight percent andthis dispersion was recirculated for another 8 hours and collected,forming Sample 2 having a micropulp content of 1.85 weight percent. Thevolume average fiber length for these samples were about 5 and 3micrometers, respectively, for the 8 and 16 hour samples. Samples aresummarized in Table 1. TABLE 1 Volume Average Fiber Length SampleRecirculation Hours Weight % Micropulp (micrometers) 1 8 2.27 5 2 161.84 3

[0050] The polymer precursor dispersion Sample 1, having 2.27 weightpercent micropulp in ethylene glycol, was used to make a polyesterpolymer having a micropulp dispersed therein. The polymer was made on a40 pound (18 kilogram) horizontal autoclave with an agitator, vacuumjets, and a monomer distillation still located above the clave portionof the autoclave. The monomer distillation still was charged with 40pounds (18 kilograms) of dimethyl terephthalate (DMT), 26 pounds (12kilograms) of ethylene glycol, and 8.8 pounds (4 kilograms) of Sample 1.Tetrapropyl titanate was used as both the exchange and polymerizationcatalyst. The temperature of the still was gradually raised to 240° C.and approximately 6000 grams of methanol distillate was recovered. Themolten prepolymer was then dropped from the monomer still to the claveportion of the autoclave. There the prepolymer was mixed, agitated, andpolymerized by increasing the temperature to approximately 280° C. Thepressure was reduced to approximately 1 mm Hg (133 Pa) over about 2hours and the material was held at these conditions for approximately 4hrs. The polymer was extruded through a 3 hole casting plate, quenchedand cut.

[0051] The polymer precursor of dispersion Sample 2, having 1.85 weightpercent micropulp in ethylene glycol, was then used to make a polyesterpolymer having a micropulp dispersed therein by repeating the abovesteps with the exception that only 1 pound (0.45 kilograms) of Sample 2was added to the monomer distillation still.

[0052] The polymer precursor of dispersion Sample 2, having 1.85 weightpercent micropulp in ethylene glycol, was then used to make a polyesterpolymer having a micropulp dispersed therein by repeating the abovesteps with the exception that 2.2 pounds (1 kilogram) of Sample 2 wasadded to the monomer distillation still.

Example 2

[0053] This example illustrates a method for making a polymer precursordispersion of micropulp in a condensation monomer, and then polymerizingthe condensation monomer to make a polymer. For this example, thecondensation monomer is 1,4-butanediol and the final polymer is acopolyetherester.

[0054] A series of samples of a nominal 1.5 weight percent micropulpdispersed in 1,4-butanediol was made by making a first mixture by adding136.8 grams of poly(paraphenylene terephthalate) pulp (KEVLAR® pulp,Merge 1F543) to 8986 grams of 1,4-butanediol and running this throughthe 1.5 liter Premier media mill as in Example 1. Due to capacitylimitations of the mix tank, while the first mixture was running throughthe mill a second mixture of an additional 6140 grams of 1,4-butanedioland 93.5 grams of pulp were added to the mix tank and this becamecombined with the first mixture. The combined mixtures were collectedtogether after a single pass and this first polymer precursor dispersioncontaining micropulp was designated Sample 3. A second polymer precursordispersion containing micropulp, Sample 4, was produced via two passesthrough the mill, after which an additional 535 g of butanediol wereadded to the remaining slurry. A third polymer precursor dispersioncontaining micropulp, Sample 5, was then produced by collecting a sampleafter 3 passes through the mill. After this sample was collected, theremaining 2-pass dispersion was put into recirculation. SubsequentSamples 6-9, respectively, were collected at 2, 4, 6 and 11 hours ofrecirculation through the mill. Because of the dilution and possiblysome evaporation, the final weight percent micropulp was measured forthese items. The results are shown in Table 2a. TABLE 2a Sample # ofPasses Recirculation Hours Weight % Micropulp 3 1   — 1.54 4 2   — 1.545 3   — 1.40 6 2+ 2 1.45 7 2+ 4 1.51 8 2+ 6 1.57 9 2+ 11 1.64

[0055] Copolyetherester polymers were made from selected samples fromTable 2a and the ingredients listed in Table 2b. Also listed in Table 2bare the ingredients for a control Sample A from which a polymer was madewithout the polymer precursor dispersion containing micropulp. For allpolymers, the ingredients from Table 2b were placed in an agitated flaskfitted for distillation and a stainless steel stirrer with a paddle cutto conform with the internal radius of the flask was positioned about 2mm from the bottom of the flask. The air in the flask was replaced withnitrogen by applying vacuum, and then re-pressurized with nitrogen. Theflask was placed in a Woods metal bath at 155° C., and agitationinitiated. The bath temperature was increased to 210° C., and it washeld at 210° C. for 40 minutes. During this time, methanol distilledfrom the reaction mixture. Then, the bath temperature was increased to250° C. over a period of 25 minutes. When the temperature reached 250°C., the pressure was gradually reduced to 200 Pa over a period of 20minutes. The polymerization mass was then agitated at 250° C. and 200 Pafor another 30 minutes. The polymer mass became more viscous, and thetorque on the stirrer increased during this time. The resultant viscousmolten polymer was scraped from the flask and allowed to cool. Samplesfor physical testing were prepared by compression molding at about 200°C. for one minute and cooling rapidly in the press. Properties for theresultant polymers are shown in Table 2c. Surprisingly, the addition ofa very minor amount of micropulp dramatically increased the mechanicalproperties of the polymer. Even more surprising and unexpected is theincrease in both elongation and stress at 40% elongation. Theseproperties normally respond by one being increased at the expense of theother. TABLE 2b Ingredient Parts Polymer Containing Micropulp DispersedTherein Poly(tetramethyleneether) glycol, 27.0 number average molecularweight of about 975 Dimethyl Terephthalate 24.2 Dimethyl Isophthalate7.0 Micropulp dispersed in 1,4-butanediol See Table 3 2% Solution ofTrimethyl Trimellitate dissolved in 1,4-butanediol 2.0 5% Solution ofTetrabutyl Titanate dissolved in 1,4-butanediol 1.2 N,N′-Hexamethylenebis(3,5-di-tert-butyl-4- 0.09 hydroxyhydrocinnamide N,N′-Trimethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamide 0.09 Control Sample APolymer Poly(tetramethyleneether) glycol, 27.0 number average molecularweight of about 975 Dimethyl Terephthalate 24.2 Dimethyl Isophthalate7.0 1,4-butanediol 18.0 2% Solution of Trimethyl Trimellitate dissolvedin 1,4-butanediol 2.0 5% Solution of Tetrabutyl Titanate dissolved in1,4-butanediol 1.2 N,N′-Hexamethylene bis(3,5-di-tert-butyl-4- 0.09hydroxyhydrocinnamide N,N′-Trimethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamide 0.09

[0056] TABLE 2c Sample Used In Polymer A 3 5 5 9 Color clear light lightlight light colorless yellow yellow yellow yellow Melt Flow 8.5 1.6 2.32.9 2.0 Index @ 190 C. Polymer 0 20 20 60 20 Precursor Dispersion(Parts) Micropulp 0 0.5 0.5 1.5 0.5 content (wt %) Thickness 49 57 57 5757 (mil) Tb (psi) 4169 5841 5098 2296 5906 Eb (%) 1271 1458 1353 5561444 Young's 7305 5517 6285 8706 4990 Modulus (psi) Toughness 2907144470 36907 10160 44398 (psi) Stress at 1067 1224 1197 1525 1184 40%Elongation (psi) Tear Peak 13.30 17.05 19.46 8.79 21.92 Load (lbf)Energy to 26.43 30.34 37.15 17.54 33.50 Tear(in-lbf)

Example 3

[0057] This example illustrates a method for making a polymer precursordispersion of micropulp in an addition monomer, and then polymerizingthe addition monomer to make a polymer. For this example, the additionmonomer is methyl methacrylate and the final polymer is a poly(methylmethacrylate).

[0058] As in previous examples, the polymer precursor dispersioncontaining micropulp was produced using a 1.5 liter Premier mill. Themix tank was filled with 7840 grams of methyl methacrylate and 160 gramsof poly(paraphenylene terephthalamide) pulp (KEVLAR® pulp, Merge 1F543).As in Example 2, due to capacity limitations of the mix tank, while thefirst mixture was running through the mill a second mixture of anadditional 4704 grams of methyl methacrylate and 96 grams of pulp wereadded to the mix tank and this became combined with the first mixture.The combined mixtures were collected together after a single pass andthis first polymer precursor dispersion containing micropulp wasdesignated Sample 10 and had a volume average length of 100 micrometers.The remaining dispersion was passed through the mill a second time, anda 2-liter sample designated Sample 11 was collected. The volume averagelength of the micropulp in this dispersion was 39 micronmeters. Theremaining dispersion was then put into recirculation through the mill.After 1 hour, another 2 liter sample designated Sample 12 was collectedand the micropulp in this dispersion had a volume average length of 12micrometers. After 2 more hours, or a total of 3 hours of recirculation,another sample designated Sample 13 of 3 liters was collected and thevolume average length of the micropulp in this precursor dispersion was3.4 microns. The samples are summarized in Table 3. TABLE 3 VolumeAverage Sample # of Passes Recirculation Hours Length (micrometers) 101   — 100 11 2   — 39 12 2+ 1 12 13 2+ 3 3.4

[0059] Each of these polymer precursor dispersions, each containingmicropulp and an addition monomer, was then each polymerized with itself(addition reaction) to produce poly(methyl methacrylate) polymer havinga micropulp dispersed therein.

Example 4

[0060] This example illustrates a method for making a polymer precursordispersion of micropulp in a prepolymer, and then polymerizing theprepolymer to make a polymer having a micropulp dispersed therein. Forthis example, the prepolymer is an emulsion and the final polymer is acopolymer of ethylene and methacrylic acid.

[0061] As in previous examples, the polymer precursor dispersioncontaining micropulp was produced in a 1.5 liter Premier mill. The mixtank was filled with 3908 grams of AQUASEAL® 1243 and 120.8 grams of wetpoly(paraphenylene terephthalamide) pulp, available from E. I. du Pontde Nemours and Company as KEVLAR® pulp, Merge 1F361 (this is 50% water,so 60.4 grams of actual pulp were actually added). AQUASEAL® is anaqueous emulsion of approximately 25 percent by weight of a copolymer ofethylene and acrylic acid (19% by weight) and 75 percent demineralizedwater containing approximately 10 percent ammonium hydroxide. Themixture was recirculated through the mill with 150 ml samples designatedSamples 14-16, respectively, of the polymer precursor dispersion takenafter 2, 4, and 6 hours of recirculation. The remainder was collectedafter 9 hours of recirculation and this was designated Sample 17.Samples are summarized in Table 4. TABLE 4 Sample Recirculation Hours 142 15 4 16 6 17 9

[0062] Polymers containing micropulp were made from each of the samplesby injecting the polymer precursor dispersion into an extrudercontaining a molten copolymer of ethylene and methacrylic acid (19% byweight) that was partially neutralized (approximately 60%) with zincions. The water was vacuum extracted from the extruder and a copolymerhaving a micropulp dispersed therein was extruded in the form ofpellets.

Example 5

[0063] This example illustrates a method for making a polymer precursordispersion of micropulp in a polymer modifier, and then incorporatingthe polymer modifier in the polymer to make a polymer having micropulpdispersed therein. For this example, the polymer modifier is oleic acidand the final polymer is a copolymer of ethylene and methacrylic acid.

[0064] The polymer precursor dispersion containing micropulp of thisexample was produced in a larger 15 liter Premier mill.Poly(paraphenylene terephthalamide) pulp (Kevlar® pulp Merge 1F543) wasmixed with oleic acid in quantities sufficient to form a 1 percent byweight dispersion of pulp in oleic acid. 188 pounds (85 kilograms) ofthe 1% dispersion was charged in the mix tank of the mill. Thisdispersion was fed to the 15 liter Premier mill at a rate of 2 lbs/min(0.9 kg/min) for a single pass through the mill and collected in anothertank. These single passes were repeated until a total of 9 passes werecompleted. Samples of approximately 5 gallons were collected after 1, 2,4, 6 and 9 passes and designated Sample 18-22, respectively, as shown inTable 5. TABLE 5 Sample # of Passes 18 1 19 2 20 4 21 6 22 9

[0065] Two polymers containing micropulp were made by injecting the9-pass polymer precursor dispersion (Sample 22) into an extrudercontaining each individual polymer. The first polymer contained moltenionomers of a copolymer of ethylene and methacrylic acid (19% by weight)and the second polymer contained molten ionomers of a copolymer ofethylene, n-butylacrylate (23.5% by weight) and methacrylic acid (9% byweight) that was partially neutralized with magnesium hydroxide. Forboth polymers the water was vacuum extracted from the extruder and apolymer having a micropulp dispersed therein was extruded in the form ofpellets.

[0066] Polymer containing micropulp were made by injecting the 9-passpolymer precursor dispersion (Sample 22) into an extruder containingmolten ionomers of a copolymer of ethylene and methacrylic acid (19% byweight) and a copolymer of ethylene, n-butylacrylate (23.5% by weight)and methacrylic acid (9% by weight) that was partially neutralized withmagnesium hydroxide. The water was vacuum extracted from the extruderand a copolymer having a micropulp dispersed therein was extruded in theform of pellets.

Example 6

[0067] This example illustrates a method for making a polymer precursordispersion of micropulp in a prepolymer, and then polymerizing theprepolymer to make a polymer having a micropulp dispersed therein. Forthis example, the prepolymer is a polyamide acid and the final polymeris polyimide. This example also illustrates one method by which asolvent can be added to the polymer precursor and then later removedafter the micropulp is formed in the polymer precursor.

[0068] To prepare the prepolymer, 4,4′-oxydianiline was solvated indimethylacetamide (DMAc) solvent and a slightly less than equal molaramount (95-99% stoichiometry) of pyromellitic dianhydride added underagitation. The mixture was agitated until the polyamide acid, which isthe prepolymer, was formed and the mixture has a viscosity of from 20 to100 poise and the prepolymer was present in an amount of 10-30 percentby weight.

[0069] As in previous examples, the polymer precursor dispersioncontaining micropulp was produced using a 1.5 liter Premier mill. Themix tank was filled with the polyamide acid prepolymer mixturecontaining DMAc and poly(paraphenylene terephthalamide) pulp (KEVLAR®pulp Merge 1F543). Additional DMAc was added to the mixture. The finalmixture was approximately 10.1 kilograms which contained about 7.5percent by weight polyamide acid prepolymer, about 1 percent by weightpoly(paraphenylene terephthalamide) pulp (KEVLAR® pulp Merge 1F543), andabout 91.5 percent by weight DMAc. This mixture was then recirculatedthrough the mill for 20 hours with 1 liter samples of the prepolymerdispersion containing micropulp being collected after 4, 8, 12, 16, and20 hours of recirculation, with the samples being designated as Samples23-27, respectively, as shown in Table 6 TABLE 6 Sample RecirculationHours 23 4 24 8 25 12 26 16 27 20

[0070] A polyimide polymer having micropulp dispersed therein is madefrom the prepolymer dispersion containing micropulp. The prepolymer isfirst “finished” by the addition of small amount of pyromelliticdianhydride with the goal being to bring the molar diamine/dianhydrideratio close to 1:1 to increase molecular weight and viscosity. Targetfinal viscosity is between 200-5000 poise. A liquid film is then cast ona smooth surface using a die casting process. Initial temperatures whilethe liquid film is on the cast surface ramp up through an oven between60° C.-200° C. over 5-60 minutes. The casting process removes DMAcsolvent and creates a free-standing film containing 70-90% solids ofmicropulp and polyamide acid prepolymer.

[0071] The prepolymer film is then converted to a polyimide polymer filmhaving micropulp dispersed therein by placing the film in a hightemperature oven for imidization at 200 to 400° C. for 5 to 60 minutes.

Comparative Example A

[0072] This example illustrates the problems experienced with attemptingto incorporate a micropulp into a high viscosity liquid polymer. Thepoly(paraphenylene terephthalamide) pulp used as a starting material inthe previous examples as added to the well-known epoxy resin EPON 828and an attempt was made to process the pulp in the epoxy resin to createa micropulp dispersed in the resin. EPON 828 has a viscosity of 11,000centipoise at room temperature and consequently was too viscous toprocess in the mill so it was not possible to make a dispersion ofmicropulp in this highly viscous resin.

What is claimed is:
 1. A polymer precursor dispersion for use in makinga polymer that is a solid at room temperature, comprising: a polymerprecursor comprising an addition monomer, a condensation monomer, aprepolymer, or a polymer modifier; and a micropulp having a volumeaverage length of from 0.01 to 100 micrometers, the micropulp comprising0.01 to 50 weight percent of the dispersion.
 2. The polymer precursordispersion of claim 1, wherein said polymer precursor has a viscosity ofless than 10,000 centipoise at room temperature.
 3. The polymerprecursor dispersion of claim 1, wherein the polymer precursor furthercomprises a solvent.
 4. The polymer precursor dispersion of claim 1,wherein the weight percent of micropulp is 0.01 to 10 weight percent. 5.A polymer made using the polymer precursor dispersion of anyone ofclaims 1-4.
 6. A shaped article comprising the polymer of claim
 5. 7. Amethod of incorporating a micropulp in a polymer precursor for making apolymer that is a solid at room temperature, comprising: contactingorganic fiber, a polymer precursor and a solid component, agitating theorganic fiber, the polymer precursor, and the solid component totransform the organic fiber into a micropulp having a volume averagelength of from 0.01 to 100 micrometers dispersed in the polymerprecursor, and optionally removing the solid component.
 8. The method ofclaim 7, wherein the polymer precursor comprises an addition monomer, acondensation monomer, a prepolymer, or a polymer modifier.
 9. The methodof claim 7, wherein the addition monomer is selected from the groupconsisting of methyl methacrylate, ethyl acrylate, styrene,acrylonitrile, and vinyl chloride; the condensation monomer is selectedfrom the group consisting of ethylene glycol, dimethyl terephthalate,diethylene glycol, 1,3 propane diol, 1, 4 butane diol, and cycolhexanedimethanol; the prepolymer is selected from the group consisting ofpolyamide acid, polyester oligomer, and emulsified polymer dispersion;or the polymer modifier is selected from the group consisting of apolymer plasticizer, a polymer additive, a polymer curing agent, apolymer property enhancer, a polymer processing aid, and a polymersurface lubricating agent.
 10. The method of claim 7, wherein saidpolymer precursor has a viscosity of less than 10,000 centipoise. 11.The method of claim 7, wherein the polymer precursor further comprises asolvent.
 12. The method of claim 11, further comprising the additionalstep of removing a portion of the solvent from the polymer precursordispersion to form a concentrated polymer precursor dispersion.
 13. Themethod of anyone of claims 7-12, further comprising forming a polymerfrom the polymer precursor having micropulp dispersed therein.
 14. Themethod of claim 13, further comprising forming an article from thepolymer.